Electrical multiplier



Nov. 23, 1965 B. w. LEE 3,219,808

ELECTRICAL MULTIPLIER Filed Sept. 7, 1962 3 Sheets-Sheet 1 FIG-lINVENTOR. 3064 144 LEE Nov. 2-3, 1965 B. w. LEE

ELECTRICAL MULTIPLIER 3 Sheets-Sheet 2 Filed Sept. 7, 1962 uwiwrl RF.ufimk mm Q MQRQQWM w QNIUPK. 7 W 4 as w ufix United States Patent3,219,868 ELECTRICAL MULTHILIER Bock W. Lee, Berkeley, Qalifi, assignorto Noller Control Systems, Inc. Filed Sept. 7, 1962. Ser. No. 221,934Ciairns. Cl. 235-194) My invention relates to a manner of multiplyingtwo factors together by the use of electrical means to produce aproduct. customarily the factors involved are electrical quantities suchas voltage and amperage and produce a product which can be read from anysuitable source of display device such as a meter.

More particularly, the invention relates to a device for takingelectrical quantities; for example, the voltage of an alternatingcurrent and the amperage of that or another alternating current, andmultiplying them together to afford a product indication, i.e. wattage.Under most circumstances, the alternating values are those which havethe usual frequency of alternation encountered in normal power lineinstallations, although other frequencies can equally well be used.

Multiplying together quantities, such as voltage and amperage, tofurnish an indication of the product, wattage, has heretofore beenelectrically accomplished only by rather special mechanism subject tovariation due to temperature changes and effective to afford a voltageout put, for example, measurable only in small quantities such asmillivolts requiring amplification for ordinary use. Devices heretoforeavailable are relatively expensive and employ relatively critical ornecessarily precise components to obtain the desired accuracy ofindication.

An object of the invention, therefore, is to provide an electricalmultiplier substantially immune to customary temperature variations andrequiring no special temperature compensation.

Another object of the invention is to provide an electrical multiplierin normal embodiment affording an immediate output measurable in voltsrather than in millivolts.

A still further object of the invention is to provide an electricalmultiplier that is substantially or practically linear over a wide rangeof input variation.

A still further object of the invention is to provide an electricalmultiplier sufiiciently versatile as to combine various factorsimpressed upon the multiplier in terms of electrical value such asvoltage and amperage.

Other objects together with the foregoing are attained in theembodiments of the invention described in the accompanying descriptionand illustrated in the accompanying drawings, in which:

FIGURE 1 is a circuit diagram showing one form of electrical multiplierpursuant to the invention;

FIGURE 2A is a plot showing variation of voltages in a pair oftransformer coils with time;

FIGURE 2B is a plot showing variation in flux in a transformer coreconsidered with respect to time;

FIGURE 2C is a plot showing a form of output wave of the electricalmultiplier prior to filtering, the plot being measured in instantaneouscurrent against time; and

FIGURE 3 is a circuit diagram of an electrical multiplier in modifiedform.

In the first form of electrical multiplier, particularly illustrated inFIGURE 1, the arrangement is such as to receive two different electricalinput factors. These factors may be voltage, amperage or combinationsthereof. The same voltage, for example, can be impressed on both inputsin order that those two input factors when multiplied together alford anindication of the square of the voltage.

As an example herein, there is provided an input cur- 3,219,838 PatentedNov. 23, 1965 rent circuit having leads 7 and 8 joined by a primarywinding 9 polarized as shown by the dot and through which, for example,a current i, flows in the instantaneous direction of the arrow 11. Thecurrent i, can be considered as an alternating current having afrequency of 60 cycles per second. The primary Winding 9 is part of atransformer 12 and is arranged in magnetic relationship to a transformercore 13.

Similarly, there is also provided a pair of conductors 16 and 17connected in a circuit and considered as a voltage input v Theconductors 16 and 17 are joined through a primary winding 18 of atransformer 19 having a core 20. While it is possible that theconductors 7 and 8 are entirely independent of the conductors 16 and 17,it is most often the case that the two pairs of conductors are connectedto the same source. By definition the winding 9 is considered as thecurrent coil and the Winding 18 is considered as the voltage coil. Thevoltage and current may be completely in phase or out of phase. Forpurposes of explanation, the wave of the current i, in the primarywinding 9 is considered to lag the wave of the voltage v, in the winding18 in the amount of 30 degrees.

Coupled magnetically to the core 20 of the voltage transformer 19 is apair of secondary windings 21 and 22 connected with a common lead 23extending to a terminal 24 at which there is provided a datum voltage Vfrom any suitable regulated supply, not shown. The secondary winding 21is in all respects equal to the secondary winding 22 and is connectedsymmetrically with respect to the lead 23, the instantaneouspolarizations being related as shown. The secondary winding 21, forexample, at one of its terminals 26 is connected by a lead 27 to one endof a primary winding 28 (N polarized as the dot indicates and formingpart of a main switching transformer 29 (T having a core 30 to which thewinding 28 is magnetically linked. Similarly, the secondary winding 22from one of its terminals 31 is joined by a conductor 32 to a primarywinding 33 (N also magnetically associated with the core 30 andpolarized as shown by the dot. Extending between the center conductor 23and the conductor 27 shunting the winding 21 are a resistor 34 and acapacitor 36. Similarly, shunting the winding 22 between the conductor23 and the conductor 32 are a resistor 37 and a capacitor 38.

One end of the primary winding 28 is joined by a lead 41 to thecollector 42 of a transistor 43 (Q The emitter 44- of the transistor 43is joined by a lead 46 to a datum point 47 of positive voltage l-Vsupplied by the voltage supply (not shown). The datum point 47 isconnected to a ground 48. The transistor 43 has a base 49 and is shuntedby a diode 51.

In a symmetrical disposition with respect to the primary Winding 33 andconnected thereto by a lead 52 is the collector 53 of a transistor 54 (QThe emitter 56 of the transistor is joined by a conductor 57 to thedatum point 47 at which the positive voltage +V is available. Shuntingthe transistor 54 is a diode 58.

The base 49 of the transistor 43 is joined by a conductor 59 to one endof a primary winding 60 (N also in magnetic relationship with the core30 and polarized as indicated by the dot. Similarly, the base 61 of thetransistor 54 is joined by a lead 62 to one end of a primary winding 63(N polarized as shown by the dot. The two primary windings 60 and 63 arejoined at a terminal 64 from whence a lead 66 extends to a terminal 67whereat the negative voltage V is available. Between the lead 66 and theterminal 67 are parallel conductors 68 and 69. In the first of these acapacitor 71 is interposed, whereas in the second one a resistor 72 isinterposed.

In the operation of this portion of the device, the transistor 43 Q andthe transistor 54 Q are alternately turned off and on at a predeterminedrate. This rate of alternate effectiveness of the two transistors isarbitrary but is chosen to be very rapid compared to the frequency atwhich the input voltage v across the conductors 16 and 17 and the inputcurrent i,-, in the conductors 7 and 8 alternates. The predeterminedrate of frequency chosen for the alternate operation of the transistorsis sufliciently rapid so that other changes in the circuit are so smallas to be practically disregarded. Stated differently, the switchingoperation takes place quickly enough to eliminate from practicalconsideration any changes which might occur during that interval inother values in the circuitry. While the switching time is measurableand appreciable in some contexts, it is so small relative to otherfactors as to be properly thought of herein as instantaneous. During thetime T that the transistor Q is conducting or on, and that thetransistor Q is nonconducting or off, the voltage then impressed on theprimary winding 23 N of the transformer 29 T is the bias voltage +Vavailable at the point 47 minus the instantaneous or short time averagevalue of the voltage v across the secondary winding 21 between theconductor 23 and the terminal 26. Stated differently, the voltage drop vis one half of the voltage drop between the terminals 26 and 31 sincethe windings 21 and 22 are equivalent.

During the time T that the transistor 54 Q is on or conducting and thatthe transistor 43 Q is off or nonconducting, the voltage impressed onthe winding 33 N of the switching transformer 29 T is equal to +V plusthe instantaneous or short time average value of v FIG- URE 2A shows thevoltages on the windings 28 N and 33 N as they vary with time. Since thewindings 28 N and 33 N alternate in effect and because of theirpolarized relationship, the magnetic flux in the core 39 of theswitching transformer 29 T operates preferably from a condition nearsaturation and varies substantially equal amounts first in one directionand then in the other, depending upon the momentarily impressed voltage.The maximum positive and negative excursions of the flux are equal.FIGURE 2B is an approximate graph of the flux variation with time and issubstantially a triangular wave.

Since the times T and T represent adjacent times in any one completeswitching interval, the relationship of impressed voltage, time and fluxlinkage change during any switching interval is as follows:

in which V is the positive voltage at the datum point 47; V is eitherthe voltage difference between the conductors 23 and 27 or 23 and 32,these quantities being equal;

N represents the number of turns of the winding 28; N

represents the number of turns of the winding 33; and o is the flux ofthe transformer 29 T In the circuity of FIGURE 1, the design is suchthat the number of turns N in the winding 28 and N in the winding 33 arethe same. Thus N and N are identical. It is therefore possible tocombine Equations 1 and 2 and write:

vim (3) It is to be noted that v becomes zero when T and T are equal. Itis of practical importance that the value of v be such that at no timeduring operation does it exceed the value of V If the requirement is notobserved, improper operation results. Since the transistors 43 Q and 54Q switch rapidly, the diodes 51 and 5'8 reduce voltage spikes that wouldotherwise occur.

During the interval T during which time the transistor 4-3 Q conducts,there is induction into a secondary winding 31 N polarized as shown bythe dot. The resulting current flows through conductors 82 and 83 and issufficient to render transistors 84 and S6 conducting. This pair oftransistors is collectively referred to as Q The conductor 83 is joinedthrough resistors 87 and 83 to the bases 39 and 91 respectively of thetransistors, whereas the conductor 82 extends to a point 92 joined tothe collec-tors 93 and 94 of these transistors.

Also magnetically linked to the switching transformer 29 T is a similarsymmetrical arrangement. Another secondary winding 101 N polarized asshown by the dot is joined by conductors 1132 and 103 to transistors 104and 1% collectively designated Q In this instance the conductor 1152 isjoined through resistors 107 and 108 to the bases 19? and 11d of thetransistors. The conductor 103 extends to a common point 111 joined tothe collector 112 of the transistor 1% and to the collector 113 of thetransistor 1116. Since at the time interval T being described thetransistor 43 Q is on, the transistors 34 and 86 Q conduct because thepolarity of the secondary winding N resulting from the voltage inducedtherein is proper for conduction. But as the transistor 54 Q is off, thepolarity of the secondary Winding 101 N is such that neither of thetransistors 164 and 106 Q then conducts. During the time interval T whenthe transistor 43 Q is oh, the winding '81 N is polarized againstconduction. The transistor as Q then is conduct-ing to energize thewinding 33 N to polarize the secondary winding 101 N and make thetransistors 111 i and 1% Q conduct. The transistors Q and thetransistors Q conduct alternately, each pair of transistors conductingwhenever the other is nonconducting. The time interval for switchingbetween the sets of transistors Q and the transistors Q; isinsignificant.

The alternating input current of i in a primary winding 9 produces asecondary current i in a secondary winding 116 forming part of thetransformer 12 T polarized as shown by the dot. The terminals 117 and118 of the transformer are shunted by a resistor 119 R The terminal 117is connected by a conductor 121 to the emitter 122 of the transistor 3while a branch 123 is connected to the emitter 124 of the transistor104. At the instant being described, the fiow of the current i;, in theconductor 121 is as shown by the arrow in the figure. The other side ofthe secondary winding 116 is connected at the terminal 118 to aconductor 131 extending to a center tap 132. A branch conductor 133includes a special resistor 134 R and terminates in the emitter 136 ofthe transistor 86. symmetrically from the center tap 132 a conductor 137extends through a special resistor 138 R to the emitter 139 of thetransistor 1%. Shunting the two conductors 133 and 137 across theresistors 134 and 138 are conductors 141 and 142 respectively leading toa positive terminal 143 A and to a ne ative terminal 144 B. Theseterminals are joined by a resistor 146 R representing the direct currentload or output, which may be a suitable meter or indicator.

Since by the operation of the transistors 43 Q and 54 Q the transistors84 and 86 Q and 104 and 1% Q; are alternately turned on and off, thecurrent i is switched first in one direction and then the other.Pursuant to the alternate operation of the transistors, current is madeto flow first in one direction and then the other in the circuitcontaining the resistors R R and the output resistance R This alternateswitching operation controlled by the transistors Q and Q is readilyeffected in response to adequate driving current from the secondarywinding 81 N and N1 N With the polarities shown in FIGURE 1, the outputvoltage as measured between the points 143A and 144B during timeinterval T is positive and during the adjacent time interval T isnegative. While in general the various resistors shown are not critical,it is important that the resistors 134R and 138R and the resistor 119Rhave a low inductance and a low temperature coefficient. Furthermore,the resistors 134R and 138R are identical in properties. Because of thisidentity, they can be interchangeably represented by the symbol RBecause at all times either the circuit portion controlled by thetransistors Q or the circuit portion controlled by the transistors Q; isconducting and the voltage drop in either portion is negligible, it isproper to say that the equivalent resistance R encountered by thecurrent i is independent of the particular transistor Q or Q; whichhappens to be conducting at any particular instant. This resistance isthe equivalent parallel resistance of R (as just defined) and of thequantity (R -l-R as follows:

The output voltage across the terminals 143 and 144; that is, across theterminals A and B, is represented as v and during the time interval T isdeveloped by that fraction of the current i flowing through R during thetime interval T and is positive. Comparably, during the time interval Tthe fraction of the current i flowing through R is reversed in directionso that the voltage v is negative during the time interval T Theindicated fraction of the current flowing through the resistance R isrepresented by i and in terms of the principal current i;, is:

The wave form of the output voltage v as developed across R is indicatedin FIGURE 2C. It has been stated that in this example the current is outof phase with the voltage by a phase angle of 30 degrees. FIGURE 2Cshows the current wave of the current i in the input conductors 7 and 8and also the current wave i flowing in the conductor 121 lagging thevoltage wave v and the voltage wave v at the indicated phase angle. Whenthese waves are in their unfiltered form the maximum excursion of thecurrent wave occurs 30 degrees later than the maximum and minimumexcursions of the voltage waves impressed upon the primary winding 28Nand the primary winding 33N Ordinarily, the output is not leftunfiltered, but rather is appropriately filtered by any standard meansand produces a filtered output as indicated by the straight line 151 inFlGURE 2C representing the net direct cur- This net value is correctwhen T and T are adjacent time intervals in any selected complete cycleor switching interval, as illustrated in FIGURE 2C.

By substituting the left-hand member of Equation 3 for the parentheticalright-hand portion of the Equation 6, there is derived:

AB 1 R l The voltage v appearing in Equations 2 and 3 can be expressedin terms of the input voltage v across the con ductors 16 and 17, and interms of the turns ratio N of the voltage transformer 19T is:

N being the ratio of the total primary turns to the total secondaryturns of the transformer 1.9T

Substituting this valve (Equation 8) for the term v in Equation 7yields:

In relating i to i,, first i is related to i and then from Equations 4and 5, i is related to i The current in the 6 secondary winding 116 ofthe current transformer 12T represented by i is:

where N is the ratio of the secondary turns of the transformer lZT tothe primary turns thereof. Further, the current i flowing in theconductor 121 is as follows:

Then taking the value of R from Equation 4 the value of i can beexpressed as:

s L Z1: Iguana.)

N.,[ 2RL+RX +RS 2RL+RX which can be written as:

i iiRsRL (15) NJRL RL+RX +R.(2RL+RX 1 The foregoing value for i can thenbe introduced into Equation 9 which yields for the value of v thefollowing:

U a a S L X 1 (16) AB 2T N A LRL L x+ s L+ s X If R represents the termwithin the brackets, Equation 16 can be represented as:

It will be noted that in any one particular circuit the value V isestablished by the regulated power supply, the value N is fixed as it isa ratio of transformer winding turns for the transformer 19T the valueof N is known because it is the ratio of turns of the windings in thetransformer ILZT and furthermore the values represented by R are allknown resistor values.

Since the relationship represented in Equation 17 is rounded on a singleswitching cycle represented by the juxtaposed time intervals T +T as setforth in Equation 3, then it follows that the net output voltage vduring that selected single switching cycle or interval is proportionalfor this very short time (approximately instantaneous) to the valuesduring that time of the product of the input voltage V, across theconductors 16 and 17 and the input current i across the conductors 7 and8. Thus, as shown in Equation 17, this circuitry in effect multipliesthe input voltage v, by the input current i and yields as a product thevoltage across the terminals 143A and 1443 represented as v Theelectrical factor or value introduced by the conductors 16 and 17 ismultiplied by the electrical factor or quantity introduced by theconductors 7 and 8 to produce their product as represented by thevoltage appearing across the terminals A and B. The circuit thusmultiplies these quantities and if they are difi'erent in kindnevertheless represents their product, whereas if they happen to be ofthe same kind and value their square is represented. Furthermore, ifthere is a phase difference between the input by the conductors 16 and17 and the input by the conductors 7 and 8, the product displayed at Aand B corresponds thereto.

It may be desired to determine the average value of v for of a second(for the 60 cycle input assumed) for any complete cycle of alternation.For this the product of i and v, is averaged for the time of one cycleand to divide and multiply by the constants in Equation 17, for:

i,= 1 sin n+0 (-1 and wherein m is 21r times the frequency and 0 is thephase angle.

I 0 1 (2N N) wherein V is in volts and cos 0 is power factor.

In an actual example, the component values are as follows: primarywinding 18, 1560 turns; each of the secondary windings 21 and 22, 50turns; each resistor 34 and 37, 120 ohms; each capacitor in 36 and 38,0.27 microfarad; the regulated power supply (not shown), 8 volts at 13to 18 milliamperes the diodes 51 and 58, silicon pulse diodes; thetransistors Q Q Q and Q, are each 2N404. The primary windings 28 and 33are each 100 turns, whereas the primary windings 60 and 63 are 50 turns.The capacitor 71 is 330 micromicrofarads. The resistor 72 is 18K. Thesecondary windings 81 and 101 each have 100 turns. The resistors 87, 88,107 and 108 are each 1.2K. The resistors 134 and 138 are each 2000 ohms.The resistor 119 is 200 ohms. The primary winding 9 of the transformer12 has 28 turns, whereas the second winding 116 has 2090 turns. Theoutput load resistor 146 is represented as 2500 ohms. In the actualexample, when a calibrated Watt meter indicates an input of 500 watts,the output voltage measured across 143 A and 144 B is 2.5 volts D.C.

The accuracy of measurement of input power depends upon the precision ordegree to which the phase angles of transformers 19 T and 12 T matcheach other. Accuracy also depends upon the degree to which resistor 134R and resistor 138 R approach identity in properties. The calibration ofthe circuit can be altered by adjusting the resistor 119 R It ispossible to revise the circuit and interchange certain portions so thatthe input i and the output i are interchanged. This is illustrated inFIGURE 3. The D.C. output voltage is given by Equation 20 but with Rbeing replaced by the term R R 2 RL In the FIGURE 3 arrangement thecurrent input i represented by an arrow, is derived from conductors 207and 208 connected to a primary winding 209 of a transformer 211 Tpolarized as shown by the dot. A secondary winding 212 of the currenttransformer, polarized as shown by the dot, is joined by leads 213 and214 shunting two resistors. One resistor 216 carries a current i havingthe sense indicated. The other resistor 217 carries a current i +i asshown. These currents occur because the principal current i has thesense shown in a circuit including a con-ductor 218 forming a loop.Connected by the conductor 218 are transistors 219 and 220 togetherreferred to as Q and transistors 222 and 223 together referred to as QExtending between center taps 226 and 227 is an output circuit includinga conductor 228 going to an output terminal 229 A and a conductor 231going to an output terminal 232 B. Between the output terminals there isrepresented a load resistance 233 and a meter 234, the output or loadresistance being represented by R Substantially as before, the conductor218 between the'transistors 219 and 220 branches to a conductor 236joined to a secondary winding 237 N having a return connector 238extending through a resistor 239 to the base 241 of the transistor 220and also extending through a resistor 242 to the base 243 of thetransistor 219. Similarly, between the transistors 222 and 223 there isa branch 244 extending through a secondary winding246 N the return beingthrough a conductor 247 connected through a resistor 248 to the base 249of the transistor 223 and also connected in parallel through a resistor251 to the base 252 of the transistor 222.

The voltage input v is derived from conductors 261 and 262 joined by aprimary coil winding 263 of a transformer 264 T The output of thistransformer is through two equal secondary windings 266 v and 267 vhaving the characteristics heretofore stated. The corresponding ends ofthe transformer secondary windings 266 and 267 are joined at a commonpoint 268 by a conductor 269 which leads to a loop conductor 271. Theother end of the winding 266 is joined by a lead 272 to the loopconductor 271, whereas the other end of the coil 267 is joined by a lead273 to the loop conductor 271. Shunting the winding 266 is a resistor274 and a capacitor 276 in parallel and comparably shunting the winding267 is a resistor 277 and a capacitor 278 in parallel.

A regulated power supply 281 V (not illustrated in detail) affords avoltage value of -V at a terminal 282 connected to the loop conductor271 by a lead 283 and positive voltage V is available at a terminal 284connected by a lead 286 to a conductor 287 one end of which goes toground 288. Another portion of the conductor 287 leads to the emitter289 of a transistor 291, the collector 292 of which is joined to one endof a primary coil 293 N The other end of the primary coil 293 is joinedto the loop conductor 271. comparably, from the conductor 287 there is aconnection 294 to the emitter 296 of a transistor 297. The collector 298of the transistor is joined to a primary winding 299 N the other end ofwhich is joined to the loop conductor 271. The power supply -V availableat the conductor 283 is also supplied through a lead 301 to a center tap302 through a branched circuit including a resistor 303 and a capacitor304. The center tap 302 is at one end of a primary coil 306 N the otherend of which extends through a lead 307 to the base 308 of thetransistor 291. Comparably, the center tap 302 is also connected througha primary winding 309 N duplicating the winding 306. A lead 311 connectsthe winding 309 to the base 312 of the transistor 297. Since all of theprimary windings 293 N 306 N 309 N and 299 N are associated magneticallywith the core 313 of a switching transformer 314 T inductive transferoccurs to the secondary coils 237 N and 246 N also associated with thecore 313 of the transformer 314.

The general operation of this circuit is as previously described. Whenan alternating voltage V is impressed across the conductors 261 and 262and when there is an alternating current flow i in the conductors 207and 208 through the primary coil 209, then there is a multiplication ofthe values of these two inputs resulting in a product which appearsacross the terminal 229 A and 232 B as indicated by the reading of themeter 234.

What is claimed is:

1. An electrical multiplier comprising a switching traansformer having afirst core, a pair of primary switching windings disposed in mirrorsymmetry on said first core, a voltage transformer having a second core,a primary voltage winding on said second core, a pair of secondaryvoltage windings disposed in mirror symmetry on said second core, apower supply having positive and negative terminals, a lead connectingthe adjacent ends of said secondary voltage windings to said negativeterminal, a pair of conductors joining each of the opposite ends of saidsecondary voltage windings to the respective opposite ends of saidprimary switching winding, a pair of primary transistors, means forconnecting the bases of said primary transistors to said negativeterminal, means for separately connecting the adjacent ends of saidprimary switching windings through the collector and emitter ofindividual ones of said primary transistors to said positive terminal, apair of secondary switching windings disposed in mirror symmetry on saidfirst core, a current transformer having a third core, a primary currentwinding on said third core, a secondary current winding on said thirdcore and having a first terminal and a second terminal, a pair ofsecondary transistors, means for connecting one end of one of saidsecondary switching windings to the collectors of said pair of secondarytransistors, means for connecting the other end of said one of saidsecondary switching windings to the bases of said pair of secondarytransistors, a pair of tertiary transistors, means for connecting oneend of the other of said secondary switching windings to the collectorsof said tertiary transistors, means for connecting the other end of theother of said secondary switching windings to the base of said tertiarytransistors, means for connecting said first terminal to the emitter ofone of said secondary transistors and to the emitter of one of saidtertiary transistors, a pair of output terminals, a conductor joiningone of said output terminals to the emitter of the other secondarytransistor, a lead joining the other of said output terminals to theemitter of the other tertiary transistor, a first resistor, a secondresistor matching said first resistor, means connecting said firstresistor in a conducting path between said emitter of said othersecondary transistor and said second terminal, means connecting saidsecond resistor in a conducting path between said emitter of said othertertiary transistor and said second terminal, and an output meterconnected across said first and second resistors.

2. An electrical multiplier as in claim 1 in which a third resistor isconnected to said first terminal and said second terminal.

3. An electrical multiplier comprising a switching transformer having asingle core, a pair of primary switching windings on said core, meansresponsive to the flux condition of said core for alternately energizingsaid primary switching windings at a predetermined frequency during twosuccessive time periods, means for varying the duration of said periodswith respect to each other in accordance with the magnitude of animpressed voltage, a pair of secondary switching windings on said core,an output meter, a source of current alternating at said frequency, andmeans controlled by said secondary switching windings for connectingsaid source of current and said output meter in opposite senses and atsaid frequency for affording a substantially unidirectional voltage dropacross said meter proportional to said impressed voltage and saidcurrent.

4. An electrical multiplier comprising a switching transformer having asingle core, a pair of primary switching windings on said core, a sourceof electro motive force alternating in direction of voltage drop at apredetermined frequency, means for impressing a fraction of said voltagedrop on one of said primary switching windings in one sense, means forimpressing an equal fraction of said voltage drop on the other of saidprimary switching windings in an opposite sense, means for alternatelysubjecting said primary switching windings to their respective fractionsof said voltage drop at a rate many times said predetermined frequency,a pair of secondary switching windings on said core, a source of currentalternating at said predetermined frequency, an output meter, means forconducting a fraction of said current to one terminal of said meterthrough one path, means for conducting an equal fraction of said currentto the other terminal of said meter through another path, and meanscontrolled by said secondary switching windings for rendering said pathsalternately effective.

5. An electrical multiplier comprising first means subjected to avoltage alternating in direction at a predetermined frequency, secondmeans subjected to a current alternating in direction at said frequency,a switching transformer having a single core, a pair of primaryswitching windings on said core, a local source of voltage difference,means for alternately subjecting said primary switching windings to saidlocal voltage difference at a rate many times said frequency and inopposite senses, means for impressing a fraction of said voltage acrosssaid first means on one of said primary switching windings to be addedtherein to said local voltage difference therein, means for impressingan equal fraction of said voltage across said first means on the otherof said primary switching windings to be subtracted therein from saidlocal voltage difference therein, a pair of secondary switching windingson said core, an output meter having two terminals, means for conductinga fraction of said current in said second means through one path to oneterminal of said meter, means for conducting an equal fraction of saidcurrent in said second means through another path to the other terminalof said meter, and means controlled by said secondary switching windingsfor rendering said paths alternately effective.

6. An electical multiplier comprising a source of voltage alternating ata frequency, a switching transformer having a single saturable core, apair of primary switching windings on said core, means for alternatelysupplying energy to said windings substantially to saturate said core,means for adding an increment to said energy for the energization of oneof said switching windings and for subtracting an equal increment fromsaid energy for the energization of the other of said switchingwindings, said increments being proportional to instantaneous values ofsaid alternating voltage, a source of current alternating at saidfrequency, a pair of secondary switching windings on said core, anoutput meter, and means including said secondary switching windings forconducting current from said source unidirectionally through said outputmeter.

7. An electrical multiplier comprising a source of voltage alternatingat a frequency, a switching transformer having a core, a pair of primaryswitching windings on said core, a source of continuous voltage, meansfor energizing said primary switching windings alternately from saidsource of continuous voltage, means for dividing said alternatingvoltage into two halves, means for adding the instantaneous value ofvoltage of one of said halves to one of said primary switching windings,means for subtracting the substantially simultaneous instantaneous valueof voltage of the other of said halves from the other of said primaryswitching windings, a source of current alternating at said frequency,an output meter, 21 pair of secondary switching windings on said core,and means controlled lay said secondary switching winding for conductingcurrent from said source alternately in two paths to affect said outputmeter unidirectionally.

8. An electrical multiplier comprising a source of voltage alternatingat a predetermined frequency, a voltage transformer having a primaryvoltage winding and two equal secondary voltage windings, means forimpressing said alternating voltage across said primary voltage winding,a switching transformer, a pair of primary switching windings on saidswitching transformer, a source of continuous voltage, means includingwindings on said switching transformer for energizing said primaryswitching windings alternately at a frequency higher than saidpredetermined frequency, means for additively energizing one of saidprimary switching windings in accordance with the instantaneous value ofthe voltage across one of said secondary voltage windings, means forsubtractively energizing the other of said primary switching windings inaccordance with the substantially simultaneous value of the voltageacross the other of said secondary voltage windings, a source of currentalternating at said predetermined frequency, a current transformerhaving a primary current winding and a secondary current winding, meansfor subjecting said primary current winding to said alternating current,a resistor shunting said secondary current winding, an output meterhaving two terminals, a pair of equal resistors joined at a midpoint andconnected to said two terminals to shunt said output meter, meansconnecting one end of said secondary current winding to said midpoint, apair of switching arrangements at one of their corresponding endsconnected to the respective ones of said terminals, means for connectingthe other end of said secondary current winding to the othercorresponding ends of said switching arrangements, a pair of secondaryswitching windings on said switching transformer, and means connectingeach of said secondary switching windings to control a respective one ofsaid switching arrangements.

9. An electrical multiplier comprising a switching transformer having asingle saturable core, a pair of primary switching windings on saidcore, means for subjecting each of said primary switching windings to arespective one of two equal portions of an unknown alternating voltagesubstantially saturating said core in opposite directions, means formodulating the saturation of said core by impressing a local voltageacross one of said primary switching windings in a sense to be addred tosaid portion of said unknown voltage therein and by impressing saidlocal voltage across the other of said primary switching windings in asense to be subtracted from said portion of said unknown voltagetherein, an output meter having two terminals, a current winding, a pairof equal resistors joined at a midpoint and connected to said twoterminals to shunt said output meter, means for connecting one end ofsaid current winding to said midpoint, means connecting the other end ofsaid current winding through a first switching arrangement to one ofsaid terminals, means connecting the other 12 end of said currentwinding through a second switching arrangement to the other of saidterminals, means including one secondary switching winding on said corefor controlling said first switching arrangement, and means includinganother switching winding on said core for controlling said secondswitching arrangement.

10. An electrical multiplier comprising a switching transformer having asaturable core, a pair of primary switching windings on said core, meanseffective at a relatively high frequency for subjecting said primaryswitching windings alternately to a predetermined voltage substantiallyto saturate said core alternately in opposite directions, meansalternately effective at a relatively low frequency for impressing oneselected fraction of an unknown voltage on one of said primary switchingwindings in a sense to be added to said predetermined voltage and forimpressing an equal fraction of said unknown voltage on the other ofsaid primary switching windings in a sense to be subtracted from saidpredetermined voltage, a pair of secondary switching windings on saidcore, an output device, a source of current alternating at saidrelatively low frequency, and means controlled by said secondaryswitching windings for conducting current from said sourceunidirectionally through said output device.

References Cited by the Examiner UNITED STATES PATENTS 2,808,990 10/1957 Van Allen. 2,979,263 4/1961 Keister 235--194 3,010,069 11/1961Mills et al 235-194 MALCOLM A. MORRISON, Primary Examiner.

1. AN ELECTRICAL MULTIPLIER COMPRISING A SWITCHING TRANSFORMER HAVING AFIRST CORE, A PAIR OF PRIMARY SWITCHING WINDINGS DISPOSED IN MIRRORSYMMETRY ON SAID FIRST CORE, A VOLTAGE TRANSFORMER HAVING A SECOND CORE,A PRIMARY VOLTAGE WINDING ON SAID SECOND CORE, A PAIR OF SECONDARYVOLTAGE WINDINGS DISPOSED IN MIRROR SYMMETRY ON SAID SECOND CORE, APOWER SUPPLY HAVING POSITIVE AND NEGATIVE TERMINALS, A LEAD CONNECTINGTHE ADJACENT ENDS OF SAID SECONDARY VOLTAGE WINDINGS TO SAID NEGATIVETERMINAL, A PAIR OF CONDUCTORS JOINING EACH OF THE OPPOSITE ENDS OF SAIDSECONDARY VOLTAGE WINDINGS TO THE RESPECTIVE OPPOSITE ENDS OF SAIDPRIMARY SWITCHING WINDING, A PAIR OF PRIMARY TRANSISTOR, MEANS FORCONNECTING THE BASES OF SAID PRIMARY TRANSISTORS TO SAID NEGATIVETERMINAL, MEANS FOR SEPARATELY CONNECTING THE ADJACENT ENDS OF SAIDDPRIMARY SWITCHING WINDINGS THROUGH THE COLLECTOR AND EMITTER OFINDIVIDUAL ONES OF SID PRIMARY TRANSISTORS TO SAID POSITIVE TERMINAL, APAIR OF SECONDARY SWITCHING WINDINGS DISPOSED IN MIRROR SYMMETRY ON SAIDFIRST CORE, A CURRENT TRANSFORMER HAVING A THIRD CORE, A PRIMARY CURRENTWINDING ON SAID THIRD CORE, A SECONDARY CURRENT WINDING ON SAID THIRDCORE AND HAVING A FIRST TERMINAL AND A SECOND TERMINAL, A PAIR OFSECONDARY TRANSISTORS, MEANS FOR CONNECTING ONE END OF ONE OF SAIDSECONDARY SWITCHING WINDINGS TO THE COLLECTORS OF SAID PAIR OF SECONDARYTRANSISTORS, MEANS FOR CONNECTING THE OTHER END OF SAID ONE OF SAIDSECONDARY SWITCHING WINDINGS TO THE BASES OF SAID PAIR OF SECONDARYTRANSISTORS, A PAIR OF TERTIARY TRANSISTORS, MEANS FOR CONNECTING ONEEND OF THE OTHER OF SAID SECONDARY SWITCHING WINDINGS TO THE COLLECTORSOF SAID TERTIARY TRANSISTORS, MEAN FOR CONNECTING THE OTHER END OF THEOTHER OF SAID SECONDARY SWITCHING WINDINGS TO THE BASE OF SAID TERTIARYTRANSISTORS, MEANS FOR CONNECTING SAID FIRST TERMINAL TO THE EMITTER OFONE OF SAID SECONDARY TRANSISTORS AND TO THE EMITTER OF ONE OF SAIDTERTIARY TRANSISTORS, A PAIR OF OUTPUT TERMINALS, A CONDUCTOR JOININGONE OF SAID OUTPUT TERMINALS TO THE EMITTER OF THE OTHER SECONDARYTRANSISTOR, A LEAD JOINING THE OTHER OF SAID OUTPUT TERMINALS TO THEEMITTER OF THE OTHER TERTIARY TRANSISTOR, A FIRST RESISTOR, A SECONDRESISTOR MATCHING SAID FIRST RESISTOR, MEANS CONNECTING SAID FIRSTRESISTOR IN A CONDUCTING PATH BETWEEN SAID EMITTER OF SAID OTHERSECONDARY TRANSISTOR AND SAID SECOND TERMINAL, MEANS CONNECTING SAIDSECOND RESISTOR IN A COMDUCTING PATH BETWEEN SAID EMITTER OF SAID OTHERTERTIARY TRANSISTOR AND SAID SECOND TERMINAL, AND AN OUTPUT METERCONNECT ACROSS SAID FIRST AND SECOND RESISTOR.